The present invention generally relates to a two-fluid nozzle, and more particularly, to a highly efficient two-fluid nozzle, which is adapted to effect a wide-angle, fanshaped atomized spray by a gas-liquid mixing system, the spray being used in cooling high-temperature objects, etc., and especially, which is adapted to effect atomization having uniform drop diameter, liquid amount and air amount across the entire spray pattern, and also which does not cause clogging, etc.
Conventionally, there has been provided such a two-fluid type nozzle as shown in, for example, FIG. 10 which is capable of forming a spray of atomizing gas and water mist across a comparatively wide range of surfaces of an object. The nozzle is composed of a nozzle 3 with a liquid inlet 1 and a gas inlet 2 formed therein, a nozzle 4 for liquid, a nozzle 5 for mixed liquid and gas, a retainer ring 6 mounted in the nozzle body 3 for retaining the liquid nozzle 4 and the mixed liquid and gas nozzle 5 in the nozzle, and a rubber O ring 7 interposed between the nozzle 3 and the liquid nozzle 4.
In the nozzle, the liquid is fed into the axial center portion of the nozzle through the liquid nozzle 4 from the nozzle 3. The gas passes through a flow passage 8 around the outer peripheral portion of the liquid nozzle 4, and is introduced into the mixed liquid and gas nozzle 5 through an orifice 9 formed in a flange on the liquid nozzle 4. The gas is mixed with the outer peripheral portion of the liquid ejected from the liquid nozzle in a gas-liquid mixing chamber 10 of the nozzle 5. The mixed gas and water are atomized by a slit-shaped discharge opening 12 in a hemispherical-shaped nozzle end face 11 as a mist of water and gas.
A two-fluid nozzle having a construction substantially similar to the above-described construction is shown in FIG. 11 and feeds the liquid into the central portion, feeds the gas into the outer peripheral portion thereof so as to mix them in the gas-liquid mixing chamber 10 near the discharge opening 12, jets the mixture from a discharge opening 12 which is the same shape as the discharge opening 12 shown in FIG. 10.
The two-fluid nozzle of the above-described construction has problems since the system feeds the liquid to the axial center portion and mixes the gas into the outer periphery of the liquid, the atomized drops become larger in diameter at the central portion of the spray and become smaller at the outer peripheral portion as shown in FIG. 12, thus resulting in unequal drop diameters across the spray.
Since the orifice 9 through which the gas enters the mixing chamber 10 is narrow, foreign materials such as dust and so on contained in the gas tend to clog the orifice 9, which is likely to cause the flow amount to be decreased and to cause a pressure loss. Since the air jetted from the orifice 9 collides with the corner portion 5a of the inner wall of the mixed gas and liquid nozzle 5, turbulence is caused and the foreign materials in the gas are likely to be accumulated in space 5a' adjacent the corner portion 5a. Especially in the conventional embodiment shown in FIG. 10, the above-described defects are serious, and the nozzle of the above-described construction further has many bent portions in the flow passage for the liquid so as to cause a pressure loss. The reduction of flow of the gas, and the pressure loss lower the negative pressure relative to the gas pressure at the jetting opening 4a of the liquid nozzle 4 and lower the ability of the liquid to mix the gas therein.
Further, since a rubber O ring is used, the durability of the nozzle is reduced, and also the number of parts is increased.
Further, in the above-described conventional nozzle, the shape of the discharge opening 12 in the nozzle end face 11 is a slit extending along a line in X--X direction of the nozzle axial line as shown, and has the end face 12b at the end of the side faces 12a perpendicular to the side faces in a Y--Y direction. The end face 12b is shaped as shown, which causes a drawback that the distribution of the gas-liquid becomes unequal and also the diameter becomes unequal. This is proved by experiments as described later conparing such a nozzle with a nozzle according to the present invention.
With respect to the shape of the discharge opening, a discharge opening can be a V-shaped slit 12' extending from the tip end position of the nozzle end face 11 to the side thereof as shown in, for example, FIG. 8(B) (disclosed, for example, in Japanese Laid-Open Patent Application Tokukaisho No. 56-100883).
The above-described V-shaped slit causes a drawback that the range of the atomized spray in which uniform distribution of water drops exist becomes narrower. This is proved by experiments as described later comparing such a nozzle with a nozzle according to the present invention. Even in a nozzle provided with the discharge opening 12', the passage of the fluid through the nozzle becomes complicated and foregin materials are eaily accumulated and cause pressure loss, and the two fluids are mixed immediately before the discharge opening, with the drawback that the mixing is not effected sufficiently, and the drop diameters are not uniform.